JP7308713B2 - antibacterial composite fiber - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyamide-based composite fiber having antibacterial properties.

Polyamide fibers are widely used in clothing applications such as carpets, towels, underwear, socks and stockings. When it is used for stockings, a yarn in which a core yarn of polyurethane fiber is covered with a polyamide fiber, or a composite fiber in which a polyamide component and a polyurethane component are eccentrically arranged in the same filament are used. In particular, composite fibers exhibit excellent crimpability and transparency.
In addition, there is an increasing demand for fibers imparted with antibacterial properties for these uses, and a method of attaching a compound having antibacterial properties to the fibers in post-processing has been adopted.
However, the method of imparting antibacterial properties by post-processing has a problem in durability because it tends to come off during washing. As a method for improving washing durability, fibers containing an inorganic antibacterial agent such as a porous material supporting silver or copper ions have been proposed.
Patent Document 1 proposes an irregular polyester fiber in which zeolite carries silver ions as an antibacterial metal component and contains an inorganic antibacterial agent having an average particle size of 5 μm or less. In addition, it has been shown that by reducing the particle size of the inorganic antibacterial agent, the spinning stability is improved, and high-quality fibers that suppress the occurrence of yarn breakage and fluff can be obtained. Patent Document 2 proposes a polyamide fiber using a polyamide resin composition carrying fine silver particles protected by a nitrogen-containing polymer. It has been shown that the antibacterial properties are good even after the dyeing process under acidic conditions because the antibacterial metal fine particles are protected by the nitrogen-containing polymer.
However, when silver ions are used as the antibacterial metal component, the silver ions are oxidized by alkali treatment or the influence of oxygen in the air in the post-process, which causes a problem of discoloration of the fibers.
Therefore, Patent Document 3 proposes a polyester fiber containing an inorganic antibacterial agent composed of a phosphate carrying silver ions and titanium dioxide as an antibacterial metal component. It is indicated that discoloration of fabric due to alkali treatment or the like can be suppressed by masking the discoloration of silver with titanium dioxide.

Japanese Patent Application Laid-Open No. 2004-360091 JP 2016-065195 A JP-A-2002-309445

However, although it is possible to impart antibacterial properties to polyamide composite fibers in the methods of containing a silver-based antibacterial agent as in Patent Documents 1 to 3, discoloration easily occurs and is difficult to suppress.
That is, in Patent Document 1, the antibacterial agent discolors when exposed to alkali. In Patent Document 2, the polyamide resin turns yellow when it is supported on the surface of the polyamide resin. In Patent Document 3, discoloration of the inorganic antibacterial agent is concealed by containing titanium dioxide, but it is difficult to conceal discoloration of the polyamide resin.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an antibacterial composite fiber that is excellent in antibacterial properties and that suppresses discoloration in alkali treatment.

The gist of the present invention is a composite fiber in which a polyamide resin containing an inorganic antibacterial agent containing at least silver as an antibacterial metal component is arranged in the sheath and a polyurethane resin is arranged in the core, ) and (b).
(a) the content of the inorganic antibacterial agent in the polyamide resin is 0.1% by mass or more and 1.2% by mass or less (b) the silver component content in the polyamide resin is 20 ppm or more and 600 ppm or less; The average particle diameter ( _D50 ) of the agent is preferably 0.1 µm or more and 5.0 µm or less. Furthermore, it is preferable that the antibacterial activity value measured by the bacterial liquid absorption method is 2.2 or more. Also, the color difference (ΔE) before and after the alkali treatment is preferably 2.0 or less. Furthermore, it is preferable that the core portion is arranged eccentrically in the cross section of the fiber, and that 85% or more and 99% or less of the core portion is covered with the sheath portion.

The antibacterial conjugate fiber of the present invention has excellent antibacterial properties and spinning stability, and can suppress discoloration in alkali treatment, so it can be suitably used for clothing such as underwear, socks, and stockings.

FIG. 1 shows an example of the cross-sectional shape of the composite fiber of the present invention.

In the antibacterial composite fiber of the present invention, the sheath is made of polyamide resin and the core is made of polyurethane resin.

The polyamide resin in the present invention is not particularly limited, and examples thereof include homopolymers and copolymers of nylon 6, nylon 66, nylon 610, nylon 10, nylon 11 and nylon 12.

The polyurethane resin in the present invention is not particularly limited, and examples thereof include homopolymers and copolymers of polyester polyurethanes, polycaprolactane polyurethanes, polycarbonate polyurethanes, polyether polyurethanes, and the like.

To the polyamide resin and polyurethane resin described above, as long as they do not inhibit the antibacterial properties, for example, ultraviolet absorbers, electrostatic agents, pigments, titanium oxide, etc. may be added, and deodorants and antifungal agents may be added. etc. may be given.

The antibacterial composite fiber of the present invention contains an inorganic antibacterial agent. The inorganic antibacterial agent in the present invention contains at least silver as an antibacterial metal component, and the content of the inorganic antibacterial agent in the polyamide resin is 0.1% by mass or more and 1.2% by mass or less. If the content of the inorganic antibacterial agent is less than 0.1% by mass, it becomes difficult to obtain sufficient antibacterial properties. If it exceeds 1.2% by mass, yarn breakage, fluffing, etc. tend to occur, making it difficult to stably produce yarn. Preferably, it is 0.3% by mass or more and 1.1% by mass or less. More preferably, it is 0.6% by mass or more and 1.1% by mass or less.

The antibacterial composite fiber of the present invention has a silver component content of 20 ppm or more and 600 ppm in the polyamide resin. If the silver component content is less than 20 ppm, it becomes difficult to obtain sufficient antibacterial properties. If it exceeds 600 ppm, the antibacterial performance is improved, but the discoloration after alkali treatment becomes large. It is preferably 100 ppm or more and 600 ppm or less, more preferably 300 ppm or more and 550 ppm or less.

The content of silver component in the polyamide resin of the present invention is a value measured using an ICP emission spectrometer CIROS CCD manufactured by Ametech.

The average particle size ( _D50 ) of the inorganic antibacterial agent of the present invention is preferably 0.1 µm or more and 5.0 µm or less. If the average particle size (D ₅₀ ) is less than 0.1 μm, the particles aggregate and become coarse when added to the polyamide resin. Similar problems also occur when the average particle diameter (D ₅₀ ) exceeds 5.0 μm. It is preferably 0.5 μm or more and 3.0 μm or less, more preferably 0.5 μm or more and 2.0 μm or less.

The inorganic antibacterial agent of the present invention preferably contains P, Mg, Al and Si. By containing P, Mg, Al, and Si, discoloration of the polyamide resin can be easily suppressed. The preferred content of each element is 20% by mass or more and 30% by mass or less for P, 5% by mass or more and 15% by mass or less for Mg, 1% by mass or more and 5% by mass or less for Al, and 1% by mass or more for Si. , 5% by mass or less.

In the antibacterial conjugate fiber of the present invention, an inorganic antibacterial agent may be added to the polyurethane resin, but the degree of surface exposure of the core is low, and it is difficult to obtain the desired effect.

The antibacterial composite fiber of the present invention preferably contains the above inorganic antibacterial agent, so that the antibacterial activity value calculated from the number of viable bacteria after culturing for 18 hours is 2.2 or more. This index is an index for evaluating antibacterial properties, and if the antibacterial activity value is less than 2.2, it is difficult to obtain the desired antibacterial properties.

The method of calculating the antibacterial activity value of the present invention was performed by the fungal liquid absorption method based on JIS L1902. Staphylococcus aureus (NBRC12732) was used as a test bacterium, and the antibacterial activity value was calculated by the following method.
Antibacterial activity value: log (Ct/Co) - log (Tt/To)
Ct: Number of viable bacteria in 3 specimens after 18 hours culture of standard cloth (average value)
Co: Number of viable bacteria in 3 specimens immediately after inoculation of standard cloth with test bacteria (average value)
Tt: Number of viable bacteria in 3 specimens after 18 hours culture of test sample (average value)
To: Number of viable bacteria in 3 specimens immediately after inoculation of the test sample with the test bacteria (average value)
However, the test establishment conditions (Ct/Co≧1.0, Tt/To≧1.0) shall be satisfied.

By containing the inorganic antibacterial agent as described above, the antibacterial composite fiber of the present invention can prevent discoloration before and after alkali treatment, and the color difference (ΔE) before and after treatment is 2.0 or less. Preferably. When ΔE exceeds 2.0, the image appears dull. In addition, poor color development tends to occur during dyeing. It is more preferably 1.5 or less.

The above-mentioned alkali treatment is a scouring process, and is an alkaline solution at 80 ° C with soaping agents (Daiichi Kogyo "Tripol" (0.2 g / L) and sodium carbonate (2 g / L) added. A 30-minute immersion treatment is applied to tubular knitting of composite fibers.

The cross-sectional shape of the antibacterial conjugate fiber of the present invention is not particularly limited, and can be appropriately set according to the desired properties and application. An irregular cross section tends to discolor as the surface area increases, making it difficult to obtain the desired effect.

FIG. 1 shows the fiber cross section of the antibacterial composite fiber of the present invention. In the cross section of the fiber, the core a has a core-sheath structure in which it is arranged eccentrically, and 85% or more and 99% or less of the outermost periphery of the core a is preferably covered with the sheath b. If the coverage of the core is less than 85%, the adhesion between the core and the sheath is insufficient, and the core and the sheath are likely to separate due to abrasion or the like. When the coverage of the core exceeds 99%, the crimp development is lowered. More preferably, the coverage is 90% or more and 97% or less. With such a fiber cross section, it is possible to have sufficient antibacterial properties while being provided with crimp development properties and suppressing discoloration.

In the antibacterial composite fiber of the present invention, the total fineness is not particularly limited, and can be appropriately set according to required properties and applications. Also, there is no particular limitation on the filament count. From the point of spinning stability, the total fineness is preferably 10 dtex or more and 50 dtex or less. More preferably 15 dtex or more and 45 dtex or less, more preferably 18 dtex or more and 40 dtex or less.

In the antibacterial composite fiber of the present invention, the strength is not particularly limited and can be appropriately set according to the required properties and applications. 0 cN/dtex or less is preferable. More preferably, it is 2.5 cN/dtex or more and 7.0 cN/dtex or less.

In the antibacterial composite fiber of the present invention, the elongation is not particularly limited, and can be appropriately set according to the required properties and applications. preferable. More preferably, it is 40% or more and 70% or less.

The antibacterial conjugate fiber of the present invention can be used alone, or in combination with other fibers such as other fibers such as other polyamide elastic crimped yarns and polyurethane covering yarns, interwoven yarns, and interwoven yarns.

Next, a preferred example of the method for producing the antibacterial composite fiber of the present invention will be described.

For the antibacterial composite fiber of the present invention, a mixed resin obtained by mixing the above inorganic antibacterial agent with the above polyamide resin and the above polyurethane resin are prepared.

As a method of mixing the inorganic antibacterial agent with the polyamide, there is a method of mixing the inorganic antibacterial agent during polymerization of the polyamide resin, or a method of kneading the inorganic antibacterial agent into the polyamide resin in advance using a twin-screw extruder and making a master chip. However, it is not limited to these.
When a master chip is used, a mixed resin of a polyamide resin and a master chip and a polyurethane resin are melted separately, discharged from a spinneret so as to have the above fiber cross-sectional shape, cooled, and stretched. , the antibacterial composite fiber of the present invention can be obtained.

The spinning temperature is preferably 225° C. or higher and 260° C. or lower, more preferably 230° C. or higher and 250° C. or lower, from the viewpoint of heat resistance and spinnability of the polyamide resin and polyurethane resin. The spinning speed is preferably 400 m/min or more and 1000 m/min or less, more preferably 500 m/min or more and 800 m/min or less.

The drawing temperature is preferably 20° C. or higher and 60° C. or lower, more preferably 25° C. or higher and 50° C. or lower, from the viewpoint of spinning stability. The draw ratio is preferably about 3.2 times or more and 3.7 times or less from the viewpoint of stable production.

In this way, the antibacterial conjugate fiber of the present invention having good antibacterial properties and spinning stability can be obtained.

EXAMPLES The present invention will be specifically described below with reference to examples, but the examples below illustrate the present invention and do not limit the present invention. Various physical properties were measured and evaluated as follows.

(1) Evaluation of spinning stability Evaluation was made according to the following criteria based on the average number of yarn breakages per 24 hours during fiber production.
○: When the number of times of thread breakage is less than 1 ×: When the number of times of thread breakage is 1 or more

(2) Measurement of fiber strength and elongation According to JIS L1013, a tensile test was performed using Autograph AGS manufactured by Shimadzu Corporation, and the fiber broke under the conditions of a measurement length of 200 mm and a tensile speed of 200 mm/min. The breaking strength and breaking elongation were measured five times, respectively, and the average value was determined as the strength and elongation of the fiber.

(3) Antibacterial Evaluation The antibacterial activity value was calculated according to JIS L1902. The calculated antibacterial activity value was evaluated according to the following criteria.
◎: Antibacterial activity value is 5.0 or more ○: Antibacterial activity value is 2.2 or more and less than 5.0 ×: Antibacterial activity value is less than 2.2

(4) Discoloration Evaluation The color difference (ΔE) was measured before and after the alkali treatment of the tubular knitted fabric made from the obtained antibacterial composite fiber using a colorimetric colorimeter (“Datacolor 800” manufactured by Datacolor). The measured ΔE was evaluated according to the following criteria.
○: When ΔE is 2.0 or less ×: When ΔE exceeds 2.0

[Example 1]
Prepare a masterbatch in which 20% by mass of an inorganic antibacterial agent having an average particle size (D ₅₀ ) of 2.0 μm is mixed with nylon 6, and the content of the inorganic antibacterial agent in the sheath is 0.4% by mass, The nylon 6 and masterbatch were mixed so that the silver component content was 200 ppm. A nylon 6 masterbatch mixed resin is used for the sheath, and a polycarbonate-based polyurethane is used for the core. A 1:1 ratio undrawn yarn was wound up. Next, the obtained undrawn yarn was drawn at a drawing temperature of room temperature and a draw ratio of 3.5 times, and was wound at a speed of 450 m/min. /2f antibacterial composite fibers were obtained. The spinning stability was good, and the antibacterial activity value of the obtained antibacterial composite fiber was 4.9 and ΔE was 0.66, which were good values. Table 1 shows the results obtained.

[Example 2]
An antibacterial composite fiber was produced in the same manner as in Example 1, except that the content of the inorganic antibacterial agent in the sheath was 0.7% by mass and the content of silver component was 350 ppm. The spinning stability was good, and the obtained antibacterial composite fiber had an antibacterial activity value of 5.9 and a ΔE value of 0.65. Table 1 shows the results obtained.

[Example 3]
An antibacterial composite fiber was produced in the same manner as in Example 1, except that the content of the inorganic antibacterial agent in the sheath was 1.0 mass % and the content of silver component was 500 ppm. The spinning stability was good, and the obtained antibacterial composite fiber had an antibacterial activity value of 5.9 and a ΔE value of 0.71. Table 1 shows the results obtained.

[Comparative Example 1]
An antibacterial composite fiber was produced in the same manner as in Example 1, except that the content of the inorganic antibacterial agent in the sheath was 1.5 mass % and the content of silver component was 750 ppm. Regarding the spinning stability, yarn breakage occurred frequently, and antibacterial composite fibers could not be obtained. Table 1 shows the results obtained.
[Comparative Example 2]
An antibacterial composite fiber was produced in the same manner as in Example 2, except that the silver content in the sheath was changed to 700 ppm. The spinning stability was good, and the antibacterial activity value of the obtained antibacterial composite fiber was 5.9, but the ΔE was 11.53, which was a large discoloration. Table 1 shows the results obtained.

[Comparative Example 3]
It was produced in the same manner as in Example 1, except that the inorganic antibacterial agent was not mixed in the sheath. The spinning stability was good and the ΔE was good at 0.23, but the antibacterial activity value was 1.3 and the antibacterial properties were not good. Table 1 shows the results obtained.

The antibacterial conjugate fibers obtained in Examples 1 to 3 exhibited excellent crimp development, good spinning stability, excellent antibacterial properties, and suppressed discoloration even in alkali treatment. On the other hand, in Comparative Examples 1 to 3, either the spinning stability or the antibacterial property was poor, or discoloration was confirmed after the alkali treatment.

Since the antibacterial conjugate fiber of the present invention has good spinning stability and antibacterial properties, and is inhibited from discoloration after alkali treatment, it can be suitably used for clothing such as underwear and stockings.

a Core part b Sheath part

Claims (5)

It is a conjugate fiber in which a polyamide resin containing at least silver as an antibacterial metal component and an inorganic antibacterial agent containing P, Mg, Al and Si is arranged in the sheath and a polyurethane resin is arranged in the core. It is an antibacterial composite fiber that satisfies (a) and (b).
(a) The content of the inorganic antibacterial agent in the polyamide resin is 0.1% by mass or more and 1.2% by mass or less (b) The silver component content in the polyamide resin is 20 ppm or more and 600 ppm or less 2. The antibacterial composite fiber according to claim 1, wherein the inorganic antibacterial agent has an average particle size ( _D50 ) of 0.1 [mu]m or more and 5.0 [mu]m or less. 3. The antibacterial composite fiber according to claim 1 or 2, wherein the antibacterial activity value is 2.2 or more by a fungal liquid absorption method. The antibacterial conjugate fiber according to any one of claims 1 to 3, characterized in that the color difference (ΔE) before and after alkali treatment is 2.0 or less. The antibacterial conjugate fiber according to any one of claims 1 to 4, wherein the core portion is eccentrically arranged in the cross section of the fiber, and 85% or more and 99% or less of the core portion is covered with the sheath portion. .

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